1. Field of the Invention
A plug connector and printed circuit board assembly and method include a snap-on fastening arrangement wherein a row of resilient contacts on the plug connector are brought into engagement with a corresponding row of strip contacts carried by a planar surface of the printed circuit board, whereupon the plug connector is fastened to the printed circuit board in such a manner as to compress the resilient contacts against the strip contacts.
2. Description of the Related Art
Various types of arrangements have been proposed in the prior art for connecting multi-contact plug connectors with circuit boards, as evidenced by the U.S. patents to Scheffner U.S. Pat. No. 5,755,822 and Endres, et al., U.S. Pat. No. 6,431,920, among others.
Owing to the pressure of constantly rising costs in the electrical industry and the attendant effort given to simplification and cost reduction for almost all structural elements, there is a need in the art for simple, non-welded means for connecting a multi-contact plug connector with a simple printed circuit board having no pin strip or socket board on the printed circuit board.
According to the present invention, an improved connector arrangement is provided including a printed circuit board having a planar surface provided with contact strips and soldering pads, and a plug connector having corresponding contacts that are made as resilient contacts, and wherein the plug connector can so be fixed to the printed circuit board by means of a snap-on locking arrangement such that the resilient contacts are compressed into contact with the contact strips and soldering pads of the printed circuit board.
As a consequence of the present invention, it is possible to avoid the use of a permanent counterpart on the printed circuit board, such as a pin strip or a solderable socket connector, and to provide a reasonably priced connector that produces positive electrical engagement with the contact strips and soldering pads on the printed circuit board without any actual soldering of the contacts to the soldering pads.
The individual resilient contacts on the plug connector can be fashioned in any desired way. For example, they can each have a contact part, which is supported on the housing of the plug connector via a resilient portion. It is particularly important to make sure that sufficient contact pressure is achieved to produce a vibration-proof contact of the contact parts, in particular, the soldering locations on the printed circuit board.
In this manner, one can reduce the number of boreholes provided in the printed circuit board, since the printed circuit board needs only to be provided with contact pads—for example, soldering pads—on its planar surface. Soldering pins, inserted in the printed circuit board as contacts, on the other hand, are no longer required. Basically, the number of boreholes can thus be reduced to the few necessary boreholes for locking the plug connector on the printed circuit board or for receiving attachment lugs on the printed circuit board.
According to a first embodiment of the invention, the plug connector includes snap-fastener pins that are designed for locking engagement with corresponding fastener apertures contained in the printed circuit board. This embodiment is particularly suitable for use with rather larger plug connectors.
The fastener elements may be connected integrally with the plug connector, or may be made as separate parts for this purpose. The separate design makes it possible for the fastener elements and the remaining plug connector in each case to use the optimum materials with regard to the requirements for the snap-fastening function or for the remainder of the plug connector.
Preferably, the fastener means includes a pair of pins on the plug connector adjacent the ends of the row of resilient contacts, and the printed circuit board merely contains the corresponding attachment holes.
Alternatively, especially for smaller plug connectors, it is also possible to provide along with the row of contact pads, at least one attachment lug that is fastened to the printed circuit board and to which the plug connector is then locked. Preferably, one attachment lug each is provided at each end of the row of contact strips and pads. In this case, the attachment lugs can then in turn include the fastener means for locking the plug connectors to the printed circuit board.
It is also possible to design the attachment lugs as surface-mounted technology attachment lugs. This offers the advantage that only parts with a relatively small mass are used and they, for example, can be set on the printed circuit board at high speed with a multi-spindle turret drill unit. The lugs can be used bilaterally on both ends of the contact pad row so that one needs to make only one type of lugs. The latter furthermore take up less space than the wider pin strips so that the user can use the space for other parts.
Another advantage when using the lugs resides in the fact that only the lugs have to be made of high-grade, high-temperature synthetic plastic material. The plug connectors, on the other hand, can consist of a more favorable plastic because they are not subjected to any heat-producing soldering operation. The wiring of the plug connectors can be handled independently of the attachment of the plug connectors on the printed circuit board also in an independent production step.
Preferably, a twisting protection is afforded for the lugs by the snap-fastener pins (in particular, by using two or more terminal pins).
According to another modification, the lugs, in a supplementary manner, include a sufficiently large suction surface for vacuum pipettes above their center of gravity. In the plug-in state, these pipettes prevent the lugs from being shifted from the soldering clamp. The length of the terminal pins of the little lugs, in particular, is so dimensioned that the reverse side of the printed circuit board can also be printed on with soldering paste. The lugs can thus be delivered ready for the automatic tape-on-reel, tray or tube packages.
It is particularly advantageous when the several attachment lugs produce a coding function and/or a polarization function by means of differing arrangement and/or geometry.